HANSER Hanser Publishers, Munich • Hanser Gardner Publications ...
HANSER Hanser Publishers, Munich • Hanser Gardner Publications ...
HANSER Hanser Publishers, Munich • Hanser Gardner Publications ...
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Table 5.2 Results of Optimization of Cooling Channel Distance in Figure 5.50<br />
Input<br />
Mold pressure<br />
Maximum deflection<br />
Modulus of elasticity<br />
Modulus of shear<br />
Allowable tensile stress<br />
Allowable shear stress<br />
Channel dimension<br />
P - 4.9 N/mm 2<br />
/max = 2.5 Um<br />
jT = 70588 N/mm 2<br />
G = 27147 N/mm 2<br />
=421.56 N/mm 2<br />
The equations given provide approximate values for circular channels as well. The distance<br />
from wall to wall of the channel should be approximately the channel length / or channel<br />
diameter, taking the strength of the mold material into account.<br />
53.6 Melting in Injection Molding Screws<br />
The plastication of solids in the reciprocating screw of an injection molding machine is<br />
a batch process and consists of two phases. During the stationary phase of the screw<br />
melting takes place mainly by heat conduction from the barrel. The melting during screw<br />
rotation time of the molding cycle is similar to that in an extrusion screw but instationary.<br />
With long periods of screw rotation, it approaches the steady state condition of extrusion<br />
melting.<br />
5.3.6.1 Melting by Heat Conduction<br />
ah<br />
D max ,<br />
Tmax =294.1 N/mm<br />
/ = 10 mm<br />
Output<br />
Channel distance<br />
Deflection<br />
Tensile stress<br />
Shear stress<br />
d =2.492 mm<br />
/ = 2.487 um<br />
G =39.44 N/mm 2<br />
T = 14.75 N/mm 2<br />
According to DONOVAN [28], the equation describing conduction melting can be written as<br />
where<br />
T = temperature 0 C<br />
A = thermal conductivity W/(m <strong>•</strong> K)<br />
K = Parameter defined by [28] m/s 0 * 5<br />
a = thermal diffusivity m 2 /s<br />
I = latent heat of fusion kj/kg<br />
p = density g/cm 3<br />
Indices:<br />
r: middle of solid bed<br />
s: solid<br />
m: melt<br />
b: barrel<br />
(5.96)